Multifunctional surgical access system

ABSTRACT

A tissue retractor comprising an outer ring, an inner ring, and a flexible, metal sheath extending therebetween is described. Embodiments of the inner ring comprise a flat or wedge-shaped conformation useful for insertion between muscle layers. Other embodiments of the inner ring include variable diameter inner rings, where the diameter can be adjusted as required and optionally locked into place, and reshapeable inner rings that permit a user to conform the inner ring to the anatomy of the patient when placing the inner ring.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/658,248, filed Jul. 24, 2017, which is a continuation of U.S. patentapplication Ser. No. 14/794,400, filed Jul. 8, 2015, now U.S. Pat. No.9,743,954, which is a continuation of U.S. application Ser. No.12/873,115, filed Aug. 31, 2010, now U.S. Pat. No. 9,717,522, whichclaims the benefit of U.S. Patent Application No. 61/238,540, filed Aug.31, 2009, the entire disclosures of which are incorporated by reference.

BACKGROUND Technical Field

This application is generally related to medical devices, and moreparticularly, to surgical access systems that include wound retractors.

Description of the Related Art

Wound retractors are used to expand or retract a surgical incision ornatural orifice. Some wound retractors comprise a polymer film sheathdisposed between an inner and outer ring. In use, the inner ring isinserted into a body cavity, such as an abdominal cavity, and the filmis anchored to the outer ring under tension. The tensioned filmstretches the incision or orifice, thereby improving access to thecavity. The polymer film sheath also lines the incision or opening,thereby protecting the soft tissue from contamination and/or physicaldamage.

SUMMARY OF THE INVENTION

A tissue retractor comprising a longitudinal axis defining an instrumentaccess channel extending from a proximal end to a distal end, an outerring, an inner ring, and a flexible sheath extending between the outerring and the inner ring, wherein the instrument access channel extendsthrough the outer ring, the inner ring, and the sheath is described.

In some embodiments, at least a portion of the cross-section of theinner ring is flat. In other embodiments, the cross-section of the innerring is flat at its outer circumference, while in other embodiments, theentire cross-section of the inner ring is flat. In still otherembodiments, the thickness of the cross-section at the innercircumference of the inner ring is greater than the thickness of thecross-section at the outer circumference of the inner ring.

In one embodiment, the inner ring comprises a single piece. In anotherembodiment, the inner ring comprises a plurality of pieces.

In one embodiment, the diameter of the inner ring is adjustable. In oneembodiment, the inner ring comprises an elongate tubular body defining alumen and wherein the tubular body comprises a first end, a second end,an opening into the lumen at the first end and an elongate shaftextending from the second end, the shaft adapted to be received throughthe opening into the lumen. Optionally, the inner ring further comprisesa locking means for locking the shaft in the lumen of the tubular bodyto thereby fix the diameter of the inner ring.

In another embodiment, the inner ring comprises an elongate C-shapedtubular body defining a channel and wherein the tubular body comprises afirst end, a second end, and an elongate shaft extending from the secondend, the shaft adapted to be received into the channel. Optionally, theinner ring further comprises a locking means for locking the shaft inthe channel of the tubular body to thereby fix the diameter of the innerring.

In still another embodiment, the inner ring is reshapeable and comprisesa plurality of linked, alternating arcuate members and straight membersdisposed end-to-end, wherein each arcuate member is rotatable relativeto an adjacent straight member around a longitudinal axis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of an embodiment of a retractor.

FIG. 1B is a side cross section of a proximal end of the retractorillustrated in FIG. 1A.

FIGS. 2A-2H and 2J-2K are cross sections of embodiments of outer rings.

FIG. 3 is a perspective view of an embodiment of a reshapeable innerring.

FIGS. 4A and 4B are perspective views of embodiments of inner rings withthinned edges.

FIG. 5 is a partial cross section of an embodiment of a collapsibleinner ring.

FIG. 6 is a detailed view of a proximal end of a retractor comprising awoven fabric sheath.

FIG. 7A is a perspective view of another embodiment of a retractor. FIG.7B is a side cross section of a proximal end of the retractorillustrated in FIG. 7A. FIG. 7C is a detail view of an outer ring andsheath of the retractor illustrated in FIG. 2A.

FIG. 8A is a perspective view of another embodiment of an unassembledretractor kit. FIG. 8B is a detail view of another embodiment of aninner ring. FIG. 8C is a perspective view of another embodiment of aninner ring.

FIG. 9A is a top view and FIG. 9B is a side view of an embodiment of anouter ring.

FIG. 10 is a partial side cross section of another embodiment of aretractor.

FIG. 11A is a perspective view and FIG. 11B is a detailed view ofanother embodiment of a retractor.

FIG. 12A is a perspective view and FIG. 12B is a detailed view ofanother embodiment of a retractor.

FIG. 13 is an exploded view of an embodiment of a retractor comprising ashield.

FIG. 14 is a top cross section of an embodiment of a resizable innerring.

FIG. 15 is a side cross section of another embodiment of a resizableinner ring.

FIG. 16 is a perspective view of an embodiment of an inner anchor.

FIG. 17A is a side view of an embodiment of a retractor comprising ametal sheath. FIG. 17B is a side view of another embodiment of aretractor comprising a metal sheath. FIG. 17C is a side view of anotherembodiment of a retractor comprising a metal sheath.

Similar reference numbers refer to similar components.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

Surgical access systems similar to embodiments disclosed herein aredisclosed in U.S. Patent Publication Nos. 2005/0241647 A1, 2007/0185387A1, 2007/0149859 A1, and 2007/0088202 A1 the disclosures of which areincorporated by reference in their entireties.

FIG. 1A is a perspective view of an embodiment of a wound retractor 100of a surgical access system. The retractor 100 comprises a proximal end102, a distal end 104, an instrument access channel 106, an outer orproximal anchor 110, and inner or distal anchor 130, and a flexiblesheath 150 extending between the outer anchor 110 and the inner anchor130. In the illustrated embodiment, both of the outer anchor 110 and theinner anchor 130 are ring-shaped, and consequently, are referred to asan outer ring 110 and an inner ring 130, respectively, in theillustrated embodiment. In the illustrated embodiment, both of the innerring 110 and the outer ring 130 are generally circular. In otherembodiments, a top or plan view of at least one of the outer ring 110and the inner ring 130 is not circular, for example, oval, elliptical,D-shaped, and the like. Furthermore, in the illustrated embodiment, theouter ring 110 and the inner ring 130 generally have the same diameter.In other embodiments, the outer ring 110 and the inner ring 130independently have different diameters, sizes, and/or shapes. Forexample, some embodiments of the inner ring 110 have a smaller diameterthan the outer ring 130, while in other embodiments, the inner ring 110has a larger diameter than the outer ring 130. The flexible sheath 150adopts the shape of the outer ring 110 and the inner ring 130.Consequently, the flexible sheath 150 in the illustrated embodiment isgenerally cylindrical.

In the illustrated embodiment, the outer ring 110 comprises an annularaxis around which the outer ring 110 is rotatable or invertible in aprocess through which the outer ring 110 is rolled through itself, aswill be discussed in greater detail below. Consequently, the outer ring110 comprises a flexible material. In some embodiments, the flexiblematerial comprises one or more polymers, for example, flexibleengineering plastics. In some embodiments, the flexible materialcomprises an elastomer, for example, a thermoplastic elastomer. In someembodiments, the outer ring 110 comprises a composite, for example, apolymer and a reinforcing material. Examples of suitable reinforcingmaterials include fibers, fabrics, and the like, which comprise at leastone of polymer, metal, glass, ceramic, and the like. Embodiments of theouter ring 110 are molded and/or extruded as a single piece or as aplurality of pieces that are assembled into the outer ring 110.

FIG. 1B illustrates a side cross section of the proximal end of theretractor 100. In the illustrated embodiment, a cross section of theouter ring 110 comprises a major or longer axis 112 and a minor orshorter axis 114. The major axis 102 is generally parallel with alongitudinal axis 118 of the outer ring 110, while the minor axis isgenerally parallel with a radial axis thereof. In other embodiments, therelative positions of the major 112 and minor 114 axes are reversed. Asbest viewed in FIG. 1B, which is a side cross-section of the outer ring110, the outer ring 110 comprises a plurality of lumens: a first lumen122 a disposed on the major axis above the minor axis, and a secondlumen 122 b, disposed on the major axis below the minor axis.Consequently, the first lumen 122 a is disposed above the second lumen122 b in the illustrated embodiment. Some embodiments of the outer ring110 comprise a different number of lumens, for example, one lumen, threelumens, or even more lumens.

In the illustrated embodiment, a cross-sectional shape of the outer ring110 is generally a figure-8, or first circle 118 a and a second circle118 b joined by a web 119 extending therebetween. The first lumen 122 ais disposed in the first circle 118 a, and the second lumen 122 b isdisposed in the second circle 188 b. Other embodiments of the outer ringhave different cross-sectional shapes, for example as illustrated inFIGS. 2A-2K, generally oval or elliptical (FIG. 2A); diamond-shaped orrhomboid (FIG. 2B); hourglass or dog bone shaped (FIG. 2C);snowman-shaped (FIG. 2D); radially flat (washer-shaped outer ring),longitudinally flat (cylindrical outer ring), or flat at another angle(frustoconical outer ring) (FIG. 2E); circular (toroidal outer ring)(FIG. 2F), X-shaped (FIG. 2G), triangular (FIG. 2H), square (FIG. 2J),hexagonal (FIG. 2K), polygonal, and the like. Some embodiments of theouter ring comprise one or more gripping surfaces 226 that facilitatemanually rolling the outer ring around the annular axis thereof.Examples of suitable gripping surfaces include generally flattenedsurfaces as shown in embodiments FIGS. 2A, 2B, 2E, 2H, 2J, and 2K; andconcave surfaces as shown in embodiments FIGS. 2C, 2D, and 2G. Any ofthe embodiments illustrated in FIGS. 2A-2K optionally comprise one ormore circumferential lumens in which wires or hoops are optionallydisposed, as discussed below. Some embodiments of the outer ring 110have a Möbius configuration in which the outer ring 110 is fabricatedwith a preloaded circumferential torsional stress, for example, bytwisting an elongate member followed by joining the ends.

In some embodiments, a wire or rod 124 is disposed in at least one ofthe first lumen 122 a and the second lumen 122 b as illustrated in FIG.1B. Embodiments of the wire or rod 124 in which the ends thereof contactor nearly contact each other in the lumen are referred to herein as a“split hoop”. Some embodiments comprise a split hoop in each of thefirst lumen 112 and the second lumen 114. In some embodiments comprisinga single split hoop 124, the split hoop 124 defines the annular axis. Insome embodiments comprising a plurality of split hoops 124, rotating theouter ring 110 around the annular axis sequentially subjects each splithoop 124 to compression followed by then tension. In these embodiments,the split hoop 124 under compression defines the annular axis for thatportion of the rotation.

In some embodiments, the split hoop(s) 124 are substantiallynon-compliant under the conditions under which the retractor 100 isused. In some of these embodiments, the split hoop(s) 124 render theouter ring 110 substantially non-compliant, for example, resistingcompression. In other embodiments, the split hoop(s) 124 are compliantand the outer ring 110 is also compliant. Some embodiments of the outerring 110 do not comprise a rod or wire disposed in a lumen thereof. Someembodiments of a non-compliant outer ring 110 facilitate direct couplingof another device to the outer ring 110 for example, a lid, cap, and/orgel cap. Some embodiments of a compliant outer ring 110 conform to abody surface.

Some embodiments of the outer ring 110 comprise a solid or non-splithoop 124 disposed in a lumen. As discussed above, in some embodiments,the solid hoop 124 defines an annular axis around which the outer ring110 is rotatable. Some embodiments of the outer ring 110 comprise asolid hoop and at least one split hoop. In some embodiments, the solidhoop and/or split hoop maintains the top- or plan-view shape of theouter ring 110, for example, circular, oval, elliptical, or D-shaped,and/or maintain a side-view profile, for example, flat, curved, orsaddle-shaped. In some embodiments, the hoop(s) 124 influence therotational characteristics of the outer ring 110, for example,preventing rotation or permitting rotation, as discussed below. In someembodiments, the hoop(s) 124 influence the orientation of the outer ring110, for example, with the major axis 112 parallel with the longitudinalaxis 116 of the outer ring 110, as illustrated in FIG. 1B, or with themajor axis 112 perpendicular with the longitudinal axis 116.

In some embodiments, a profile or graph of a potential energy of theouter ring 110 versus rotation around the annular axis over 360°comprises at least one lower energy rotational position and at least onehigher energy rotational position. For example, the configurationillustrated in FIGS. 1A and 1B is the lower energy rotational positionfor the illustrated embodiment. In the illustrated embodiment, in each360° rotational cycle, the outer ring 110 has two lower energyrotational positions, or potential energy valleys, about 180° apart inwhich the major axis is generally parallel with the longitudinal axisthereof, and two higher energy rotational positions or potential energypeaks about 180° apart in which the major axis is generally parallelwith the radial axis thereof. Consequently, the higher energy and lowerenergy rotational positions are about 90° apart. Some embodiments of theouter ring 110 have a potential energy profile that is generallysinusoidal, while the potential energy profile of other embodiments ofthe outer ring 110 has a different shape, for example, generallysaw-tooth, step-function, combinations thereof, or another suitableprofile. Embodiments of outer rings 110 with different cross-sectionalshapes have different potential energy profiles.

A consequence of the potential energy profile discussed above isreferred to as “snap action” in the annular rotation of the outer ring110. Absent any applied rotational force, the outer ring 110 adopts alow energy geometry or potential energy valley as an equilibrium ordetent position. Applying an annular torque to the outer ring 110rotates or rolls the outer ring 110 around the annular axis, therebyincreasing the potential energy of the outer ring 110, until the outerring 110 reaches the higher energy rotational position and potentialenergy peak. As the outer ring 110 passes over the potential energypeak, the stored potential energy therein is released as the outer ring110 “snaps-to” or adopts the lower energy rotational position in fallinginto the next potential energy valley. Consequently, the outer ring 110resists rotation out of the low energy rotational positions and snapsinto the low energy rotational or detent positions when perturbedtherefrom.

In a first direction of rotation referred to as “inversion” or “rollingin”, the top of the outer ring 110 passes downwardly through the openingthereof. In a second direction of rotation referred to as “eversion” or“rolling out”, the bottom of the outer ring 110 passes upwardly throughthe opening thereof. In some embodiments, the potential energy profileis generally symmetrical with respect to the direction of rotation. Inother embodiments, the potential energy is not symmetrical, for example,steeper from valley to peak when rotating in one direction than whenrotating in the opposite direction. For example, in some embodiments,inversion requires a greater force than eversion. Some embodiments ofouter rings 110 with unsymmetrical potential energy profiles haveunsymmetrical cross sections.

Returning to FIG. 1A, the inner ring 130 is deformable, comprising aflexible material, for example, a polymer for example, a flexibleengineering plastic. In some embodiments, the polymer is an elastomer,for example, a thermoplastic elastomer. In some embodiments, the innerring 130 is reshapeable, for example, comprising a plasticallydeformable or malleable elements, for example, metal and/or shape memorywires, strips, mesh, and the like. In some embodiments, the deformableelements are pleated or folded, for example, in an accordion fold or afan fold. Some embodiments of the reshapeable inner ring 130 compriseclay, powders, granules, beads, and the like disposed in a covering orenvelope. Some embodiments of the reshapeable inner ring 130 compriselinked elements—for example, a link chain, a ball-and-socket chain, or aroller chain—covered, for example, with a flexible polymer. FIG. 3 is aperspective view of an embodiment of a reshapeable inner ring 330comprising linked, alternating arcuate members 342 and straight members344, disposed end-to-end, defining a closed loop. Each arcuate member342 is rotatable relative to an adjacent straight member 344 around alocal longitudinal axis, resulting in a reshapeable inner ring 330.Other embodiments comprise different numbers of arcuate 342 and straight344 members. In some embodiments, the length of each of the arcuate 342and straight 344 members is independently selected. In some embodimentsthe angle subtended by each arcuate member 342 is independentlyselected. Some embodiments comprise fewer or no straight members 344. Insome embodiments, a conformation of the inner ring 330 is lockable, forexample, by applying tension or compression to the inner ring 330.Reshapability permits a user to conform the inner ring 330 to theanatomy of the patient when placing the inner ring 330.

In the embodiment illustrated in FIG. 1A, a cross section of the innerring 130 is generally circular. In other embodiments, the inner ring 130has another cross section, for example, oval, elliptical, flat,D-shaped, or any profile illustrated in FIGS. 2A-2K for the outer ring110. The cross section of some embodiments of the inner ring is thinnedand/or flattened at least at the outer edge 432, for example, a flat orthin wedge, resulting in an inner ring 430 with a washer-like shape asshown in FIGS. 4A and 4B. The flattened outer edge permits a user tomanipulate the edge into tight spaces when placing the inner ring 430,for example, between muscle layers. Embodiments of the inner ring 130are molded and/or extruded as a single piece, or as a plurality ofpieces that are assembled into the inner ring 130.

Some embodiments of the inner ring 130 are collapsible and/or foldable,which facilitates inserting and/or removing the inner ring 130 throughan incision or opening. For example, some embodiments comprise at leastone notch, hinge, and/or weak point, which facilitates folding thereof.Some embodiments of the inner ring 130 disassemble, thereby permittingcollapse of the inner ring 130. For example, in some embodiments, theinner ring 130 comprises a member comprising two free ends that arebrought together and coupled, thereby circularizing the inner ring 130.In some of these embodiments, the coupled free ends are disassembled,thereby collapsing the inner ring 130. In some embodiments, the freeends are coupled using a mechanical fastener, for example, at least oneof a pin, a clip, a clasp, key, or the like. In some embodiments, thefastener comprises a breakable element, for example, a tab, that bridgesthe free ends. Disengaging or breaking the fastener uncouples the freeends.

In other embodiments, the inner ring 130 comprises an annular membercoupled to a stiffening member. Disengaging and/or removing thestiffening member permits the annular member to collapse. For example,in some embodiments, the stiffening member comprises a ring-shapedportion around which the annular member is engaged. For example, in theembodiment illustrated in FIG. 5, the annular member 534 of the innerring 530 comprises a C-shaped cross section with the opening of theC-shape generally facing the longitudinal axis of the annular member534, and at least a portion of the stiffening member 536 fits within theC-shape. In other embodiments, the opening of the C-shape faces anotherdirection, for example, proximally, distally, or away from thelongitudinal axis. Removing the stiffening member 536, for example, bypulling on a tether secured thereto, as discussed below, permitscollapsing the annular member 534. In other embodiments, the stiffeningmember engages only a portion of the annular member. Again, removing thestiffening member permits collapsing the annular member.

In some embodiments, the inner ring 130 is inserted into a body cavityin the collapsed or folded state, then reconfigured into the retractingor deployed state therein.

Some embodiments of the inner ring 130 comprise a tether securedthereto. The tether facilitates removal of the inner ring 130, forexample, by pulling. In some embodiments, the tether facilitates foldingor collapsing the inner ring. For example, in some embodiments, pullingthe tether draws together portions of the inner ring 130 on either sideof a notch, hinge, or weak point thereof, thereby folding the inner ring130 and facilitating removal thereof. In some embodiments, the tether issecured to a mechanical fastener coupling the free ends of the innerring 130 together. For example, in some embodiments, the tether removesor pulls free a pin, clip, or clasp, thereby unsecuring the free endsfrom each other. In some embodiments, the tether is coupled to abreak-away element bridging the free ends of the inner ring 130 andbreaks the break-away element when pulled, thereby unsecuring the freeends. In some embodiments, the tether is secured to a stiffening memberof the inner ring 130, and pulling the tether disengages the stiffeningmember from the annular member, thereby permitting the annular member tocollapse.

In the embodiment illustrated in FIGS. 1A and 1B, the sheath 150 isgenerally a cylindrical tube with a diameter substantially equal toinside diameters of the outer ring 110 and the inner ring 130. In otherembodiments, the sheath 150 is not cylindrical, for example,frustoconical, hourglass-shaped, D-shaped, oval, combinations, and thelike. In some embodiments, the sheath 150 is fabricated as a seamlesstube. In other embodiments, the sheath 150 comprises at least one seam.In some embodiments, the sheath 150 comprises longitudinal pleats. Insome embodiments, the sheath 150 comprises at least one longitudinalslit. In some embodiments, the sheath 150 comprises a plurality ofbands, strips, and/or sheets extending between the outer ring 110 andthe inner ring 130. The bands, strips, and/or sheets extendlongitudinally and/or at a bias. In some embodiments, edges of adjacentbands, strips, and/or sheets overlap, thereby defining a tubularstructure. In some embodiments, the sheath 150 comprises both a tubularcomponent as well as at least one band, strip, and/or sheet. In some ofthese embodiments, at least some of the edges of adjacent bands, strips,and/or sheets do not overlap. A first end of the sheath 150 is coupledto the outer ring 110 and a second end of the sheath 150 is coupled tothe inner ring 110.

The flexible sheath 150 comprises an abrasion and/or puncture resistantmaterial. The abrasion and/or puncture resistance of the sheath 150improves the performance and reliability of the retractor 100 inprocedures using sharp and/or pointed instruments, and/or prostheticdevice, for example, in orthopedic procedures including hip procedures,hip replacement, and spinal procedures. Some of these procedure useinstruments such as chisels, drills, rasps, scalpels, and the like.Embodiments of the retractor 100 are also useful in other types ofprocedures, for example, arthroscopic surgery, and even abdominalsurgery. Embodiments of the abrasion and/or puncture resistant thesheath 150 protect the incision and/or opening in the body wall andsurrounding tissue from damage from the instruments used in the surgicalprocedure. Some embodiments of the sheath 150 also reduce contaminationin the surgical site, for example, from external bacteria, from tissuesremoved from the patient's body, and from surgical instruments andsupplies.

Embodiments of at least one portion of the sheath material have apuncture resistance of at least about 16 N (3.6 lb) underFED-STD-101/2065 (Puncture Resistance and Elongation Test). Someembodiments of the sheath material have a puncture resistance of atleast about 20 N (4.5 lb), at least about 30 N (6.7 lb), at least about40 N (9 lb), at least about 50 N (11 lb), at least about 60 N (13.5 lb),or at least about 100 N (22.5 lb).

Example 1

Puncture resistance was measured according to FED-STD-101/2065 for apolyurethane laminated fabric (PUL-2 mil, Seabright) comprising apolyester knit fabric and a 50 μm (2 mil) polyurethane layer laminatedto one face of the fabric. In the test, a 3.175 mm (0.125 in) roundedshaft was contacted with a 7.6 cm×7.6 cm (3 in×3 in) fabric sample at7.6 cm/min (3 in/min). The force at penetration is the penetrationresistance. The test was performed on 15 samples with the rounded shaftcontacting the polyester face of the fabric with an average punctureresistance of 61.07 N (13.73 lb). The average puncture resistance for 15tests on the polyurethane side was 53.56 N (12.04 lb).

Example 2

Puncture resistance of a 76 μm (4 mil) polyether polyurethane film(PELLETHANE® 2363, Lubrizol) used in current retractor sheaths wasmeasured as above. The average for 15 tests was 12.46 N (2.80 lb).

Embodiments of the sheath comprise sheets, membranes, fibers, and/orstrands of one or more materials that endow the sheath with the abrasionand puncture resistance. Suitable sheets, membranes, fibers, and/orstrands comprise at least one of natural polymers, semi-syntheticpolymers, synthetic polymers, metal, ceramic, glass, carbon fiber,carbon nanotubes, and the like. Suitable natural polymers includecellulose, silk, and the like. Semi-synthetic fibers includenitrocellulose, cellulose acetate, rayon, and the like. Suitablesynthetic fibers include polyester, aromatic polyester, polyamide(NYLON®, DACRON®), aramid (KEVLAR®), polyimide, polyolefin, polyethylene(SPECTRA®), polyurethane, polyurea, polyvinyl chloride (PVC),polyvinylidene chloride, polyether amide (PEBAX®), polyether urethane(PELLETHANE®), polyacrylate, polyacrylonitrile, acrylic, polyphenylenesulfide (PPS), polylactic acid (PLA),poly(diimidazopyridinylene-dihydroxyphenylene) (M-5);poly(p-phenylene-2,6-benzobisoxazole) (ZYLON®), liquid crystal polymerfiber (VECTRAN®), and the like, and blends, copolymers, composites, andmixtures thereof. Suitable metals include stainless steel, spring steel,nitinol, super elastic materials, amorphous metal alloys, and the like.

FIG. 6 is a detailed view of a portion of the outer ring 610 and sheath650, which comprises a fabric or textile. In some embodiments, thefabric or textile comprises, for example, at least one of a wovenfabric, a non-woven fabric, a knit fabric, a double-knit fabric, a mesh,a braided fabric, and a braided mesh fabric. Suitable fabrics comprisemonofilament fibers and/or yarns. Other suitable fabrics comprisetwisted and/or braided yarns. Suitable yarn materials are described inthe previous paragraph. Some embodiments of the fabric comprise acombination of fibers, for example, different warp and weft yarns inwoven or mesh fabrics, or a combination of yarns in knit or braidedfabrics. Some embodiments of the fabric are substantiallynondistensible, while other embodiments are distensible. In someembodiments, the fabric resists tear propagation in the event of damagethereto, for example, from inadvertent puncturing or cutting by asurgical instrument, or from purposeful puncturing in securing thesheath 150 as described below. Examples of such fabrics include rip-stopfabrics, certain knits, double knits, and braided mesh fabrics. In someembodiments, the orientation of fabric reduces the likelihood ofsnagging or otherwise obstructing an instrument as it is insertedthrough the sheath. For example, in some embodiments, a smoother surfaceof the fabric faces a longitudinal axis or inside of the sheath. In someembodiments, the fabric is oriented on a bias, or with ridges or troughsgenerally parallel with the longitudinal axis of the sheath. Examples ofsuitable fabrics include rip-stop polyamide (Nylon®), Oxford weavefabrics, abrasion-resistant polyester and/or polyamide fabrics(Cordura®), braided monofilament fabrics, and the like.

Some embodiments of the sheath material comprises a composite comprisinga fabric or textile, for example, at least one of a coated fabric, alaminated fabric, and a fabric embedded in a polymer. Coatings and/orlaminations are disposed on one face or both faces of the fabric.Suitable coatings and laminating materials include polymers, forexample, at least one of polyurethane, polyether, PVC, polyvinylidenechloride, silicone, styrene-butadiene, polyethylene, polypropylene,ethylene-propylene copolymer, polyisoprene, ethylene vinyl acetate(EVA), ethylene-propylene-diene monomer (EPDM), polyamide (MYLAR®),polyether block amide (PEBAX®), polyether urethane (PELLETHANE®),composites, blends, mixtures, and the like. An example of a suitablecomposite fabric is polyurethane laminated fabric (PUL). Someembodiments of the coating or lamination modify gas and/or moisturepermeability through the sheath material, for example, by controllingthe size of pores therethrough. For example, decreasing moisturepermeability reduces dehydration of the retracted tissue and/or createsa barrier to pathogens such as bacteria. Increasing gas and moisturepermeability permits hydrating and/or oxygenating the retracted tissue.Some materials are selectively permeable to certain fluids. For example,some embodiments of PVC are oxygen permeable and moisture impermeable,thereby permitting simultaneously oxygenating tissue while reducingdehydration. Some embodiments of the coating or lamination comprise anantibacterial or antimicrobial agent. In some embodiments, theantibacterial or antimicrobial agent is a surface agent or is integralto the material. Examples of suitable antibacterial or antimicrobialagents include iodine, antibiotics, silver, triclosan, biocides, and thelike. Some embodiments of the coating or lamination provide a smootherand/or lower friction inside surface, which reduces the likelihood ofinstrument damage to the sheath 150.

Some embodiments of the sheath 150 comprise a composite comprising afiber-reinforced polymer film or membrane. Suitable fibers or strandsare discussed above. Suitable polymer film materials include at leastone of materials discussed above as coating and laminating materials. Insome embodiments, the fibers are sandwiched between polymer film layers.In some embodiments, the polymer film layers are independently selected.For example, in some embodiments, the outer layer provides desirabletissue contact properties discussed above, while the inner layer ispuncture resistant.

Some embodiments of the sheath 150 comprise a plurality of layers, forexample, a fabric layer and a polymer film layer, or a fabric layersandwiched between polymer film layers. In some embodiments, the layersare secured to each other. In other embodiments, the layers areindependent of, or not secured to each other, for example, a polymerfilm layer and a layer comprising a plurality of strips or bands asdiscussed above.

Some embodiments of the sheath 150 comprise a fluid-permeable layerdisposed on a fluid-impermeable layer, with the fluid-impermeable layerdisposed on the inside of the sheath 150. The fluid-permeable layercontacts the wound margins, thereby permitting a user to supplypressurized fluid and/or apply vacuum to the wound margins. For example,in some embodiments, oxygen, moisture, therapeutic agent, and/or otherfluids are supplied to the wound margins. In some embodiments, applyingvacuum promotes bleeding, thereby reducing tissue necrosis. Embodimentsof the fluid-permeable layer comprise at least one of open cell foam,fabrics, non-woven fabrics, and knit fabrics.

In other embodiments, the sheath 150 is stretchable longitudinally. Insome embodiments, longitudinal and circumferential stretchcharacteristics of the sheath 150 are the same, that is, the stretch isisotropic. In other embodiments, longitudinal and circumferentialstretch characteristics of the sheath 150 are different, that is, thestretch is anisotropic. For example, in some embodiments, the sheath 150has greater circumferential stretch than longitudinal stretch.

In other embodiments, the sheath 150 has substantially no or littlelongitudinal stretch, that is, is non-distensible longitudinally.Consequently, a retraction force exerted on an incision or opening bythe sheath 150 remains substantially constant over the course of aprocedure. In some embodiments, the sheath 150 is radially orcircumferentially expandable. For example, some embodiments of a tubularsheath 150 comprise a woven material, as discussed below, that isexpandable or stretchable circumferentially, that is, perpendicular tothe longitudinal axis. Some embodiments comprise an elastomeric membraneor film, and longitudinal non-stretchable elements. For example, someembodiments of the sheath 150 comprise a composite comprising anelastomeric film and longitudinally disposed, non-stretchable fibers, asdiscussed above. The fibers make the sheath 150 longitudinallynon-stretchable, while the polymer film permits radial expansion.Embodiments of the sheath 150 comprising non-stretchable longitudinalstrips and an elastomeric membrane are also longitudinallynon-stretchable and radially expandable. Embodiments of a sheath 150comprising a non-stretchable tube comprising one or more longitudinalslits and/or pleats are longitudinally non-stretchable and radiallyexpandable. Embodiments of a sheath 150 comprising a plurality ofnon-stretchable longitudinal strips or bands are also longitudinallynon-stretchable and radially expandable.

In some embodiments, at least a portion of the sheath 150 is transparentor transparent, thereby providing a view of the retracted tissue. Insome embodiments comprising a polymer membrane or film, the polymermembrane or film is transparent or transparent.

In some embodiments, the sheath 150 comprises a proximal portion 152with different properties than a distal portion 154 thereof. Forexample, in some embodiments, the proximal portion 152 has greaterflexibility than the distal portion 154, thereby facilitating winding orrolling the sheath 150 around the outer ring 110. In other embodiments,the proximal portion 152 comprises one of a hook and a loop of ahook-and-loop fastener, thereby providing adjustability in embodimentsusing hook-and-loop fasteners, discussed below. Some embodiments of thesheath 150 further comprise a middle portion 156 disposed between theproximal 152 and distal 154 portions. For example, some embodiments ofthe proximal portion 152 and the distal portion 154 of the sheathcomprise a tear-resistant material for use with outer rings 110 andinner rings 130 comprising teeth, as described below. In someembodiments, the proximal portion 152 and the distal portion 154 of thesheath comprise an elastomeric material, and the middle portioncomprises a longitudinally non-distensible material, as described above.

FIG. 7A is a perspective view and FIG. 7B is a side cross section ofanother embodiment of a wound retractor 700 that is generally similar tothe embodiment described above. The retractor 700 comprises an outerring 710, an inner ring 730, and a sheath 750. In the illustratedembodiment, the outer ring 710 has a larger diameter than the inner ring730. Consequently, the sheath 750 is generally frustoconical orfunnel-shaped, tapering or converging from a proximal end, coupled tothe outer ring 710, to a distal end, coupled to the inner ring 730.Also, the outer ring 710 has a generally oval shape rather than thefigure-8 shape of the embodiment illustrated in FIGS. 1A and 1B. Asshown in a detailed view of the outer ring 710 and sheath 750 in FIG.7C, the sheath 750 comprises a knit fabric in the illustratedembodiment.

The embodiment of the retractor 700 is useful in procedures in which theinner ring 730 is inserted through a smaller body opening. The largerouter ring 710 improves protection of the body opening and surroundingtissue. Examples of such procedures include orthopedic hip replacement,vaginal retraction, and rectal retraction.

Other embodiments of the retractor comprise at least one of an outeranchor member and an inner anchor member different from the embodimentsdescribed above.

FIG. 8A illustrates a perspective view of another embodiment of aretractor 800 generally similar to the embodiments described above. Inthe illustrated embodiment, an outer ring 810, inner ring 830, andsheath 850 are unassembled. The illustrated retractor 800 is provided asseparate components, which are assembled by the user. For example, insome embodiments, individual components are selected from a kitaccording to the requirements of a particular procedure. For example,embodiments of the kit comprise at least one of outer rings 810 withdifferent diameters, inner rings 830 with different diameters, sheaths850 with different diameters, sheaths 850 with different lengths,sheaths comprising different materials, and the like. In someembodiments, the retractor 800 is disassemblable, and one or more of theouter ring 810, the inner ring 830, and the sheath 850 is reusable, forexample, autoclavable.

The outer ring 810 is illustrated in a non-circularized configuration.In the illustrated embodiment, ends of the non-circularized outer ring810 are coupled using a coupler 820. The outer ring 810 comprises aplurality of fasteners 812, which secure the sheath 850 to the outerring 810. The inner ring 830 is also in a non-circularizedconfiguration, and comprises a circumferentially facing pin or peg 842on a first end thereof, and a corresponding circumferentially facingopening 844 disposed on a second end. The inner ring 830 also comprisesa plurality of fasteners 832, which secure the sheath 850 to the innerring 830. In the illustrated embodiment, the fasteners 812 and 832comprise hooks, which puncture the sheath 850, thereby securing thesheath to the outer ring 810 and inner ring 830, respectively. In someembodiments, the fasteners 812 and/or 833 are bendable, which permits auser to further secure the sheath 850. In other embodiments, each of theouter ring 810 and inner ring 830 independently comprises fasteners forthe sheath 850, for example, hooks, clips, clamps, pins, wires,hook-and-loop fasteners, laces and eyelets, and the like. For example,in some embodiments, the fastener comprises a wire that passes througheyelets disposed on both the sheath 850, and the outer ring 810 or theinner ring 830. In other embodiments, the outer ring 810 and/or innerring 830 comprises two interlocking rings that capture the sheath 850therebetween, thereby securing the sheath thereto. In some embodiments,the interlocking rings snap together, screw together, clip together, andthe like.

In the illustrated embodiment, the inner ring 830 comprises apin-and-hole 842 and 844 system that couples together the free endsthereof. FIG. 8B is a perspective view of an inner ring 830 comprisinganother embodiment of a pin-and-hole system comprising a plurality ofsections, each comprising pins 842 disposed on both ends of the innerring 830 and corresponding, mating holes 844 disposed on both ends ofthe inner ring 830, which permit a user to couple the free ends of theinner ring 830.

FIG. 8C is a perspective view of another embodiment of an inner ring 830comprising a pin-and-hole system comprising a radial hole 844 disposedon each free end of the outer ring 830, which together with a pin (notillustrated), couple the free ends of the inner ring 830. As discussedabove, some embodiments of the retractor 800 comprise a tether suitablefor pulling a pin free, thereby collapsing the inner ring 800.

Those skilled in the art will understand that similar arrangements forcircularizing the outer ring 810 and the inner ring 830 described aboveconjunction with the embodiments illustrated in FIGS. 8A-8C are alsoapplicable to the inner ring 830 and the outer ring 810, respectively.In the embodiment illustrated in FIG. 8A, the outer ring 810 isrotatable around an annular axis thereof. In other embodiments, theouter ring is not rotatable around an annular axis. In some of theseembodiments, the sheath 850 is not tensioned by wrapping around theouter ring 810. Instead, the sheath 850 is threaded through a portion ofthe access channel extending through the center of the outer ring 850,then tensioned by pulling the sheath 850 distally from the inner ring830. The tension is maintained by engaging the sheath 850 to thefasteners 812, hooks in the illustrated embodiment.

FIG. 9A is a top view and FIG. 9B is a side view of another embodimentof an outer ring 910 comprising a lower flange 914, a concentric upperflange 916, and a plurality of fasteners or hooks 912 extending radiallyoutwards and distally from the upper flange 916. The outer ring 910 isrigid or semi-rigid and is not rotatable around an annular axis. In use,a proximal end of the sheath is threaded proximally out through aportion of an access channel 906 extending through the outer ring 910,pulled proximally, thereby tensioning the sheath, and the sheath engagedto the hooks 912, thereby maintaining a desired tension on the sheath.In the illustrated embodiment, the hooks 912 are blunt and do notpenetrate the sheath. In other embodiments, the hooks 912 are pointedand penetrate the sheath.

FIG. 10 is a side partial cross section of another embodiment of aretractor 1000, similar to the embodiments described above, comprisingan outer anchor 1010, an inner anchor 1030 and a sheath 1050. In theillustrated embodiment, the outer anchor 1010 comprises a proximal ring1012 and a distal ring 1022, which nest together. The nesting surfaces1014 and 1024, respectively, are frustoconical or wedge-shaped, with adistal diameter smaller than a proximal diameter. In some embodiments,at least a portion of the nesting surfaces 1014 and 1024 comprise steps.With the sheath 1050 disposed between the proximal ring 1012 and thedistal ring 1014 as shown in FIG. 10, pulling the sheath 1050 distally,for example, when the sheath 1050 is under tension while retractingtissue, draws the proximal ring 1012 distally, thereby seating thenesting surface 1014 of proximal ring 1012 against the nesting surface1024 of the distal ring 1024. This wedging action locks the sheath 1050between the proximal ring 1012 and the distal ring 1022, therebyresisting further distal movement of the sheath. In contrast, the sheath1050 is freely movable proximally because the sheath motion unseats theproximal ring 1012 from the distal ring 1024. In the illustratedembodiment, a gripping element 1052 is disposed at a proximal end of thesheath 1050, which improves a user's grip when applying traction ortension to the sheath 1050.

FIG. 11A is a perspective view of another embodiment of a retractor1100, generally similar to the embodiments described above, comprisingan outer ring 1110, an inner ring 1130, and a sheath 1150. In theillustrated embodiment, the sheath 1150 comprises a tubular membrane1152 extending between the outer ring 1110 and the inner ring 1130, anda plurality of elongate bands 1160, each comprising a proximal end 1162and a distal end 1164. The distal end 1162 of the band 1160 is securedto the distal ring 1130. The proximal end 1162 comprises a ladder-likesection comprising a plurality of rungs defining opening 1166 (FIG. 11B)therebetween. The proximal ends 1162 extend through an access channel1106 and through the outer ring 1110. As shown in FIG. 11B, which is adetail view of the outer ring 1110 and proximal end 1162 of a band 1160,the outer ring 1110 further comprises a plurality of fasteners or hooks1112 dimensioned to engage the openings 1166 in the proximal end 1162 ofthe band 1160, thereby maintaining a desired tension or retraction forcebetween the outer ring 1110 and inner ring 1130. Some embodiments of theouter ring 1110 comprise a greater number of hooks 1112 than the numberof bands 1160, which provides greater flexibility in engaging each band1160 to the outer ring 1110.

FIG. 12A is a perspective view of an embodiment of a retractor 1200generally similar to the embodiments described above, and in particular,to the embodiment illustrated in FIGS. 11A and 11B. The retractor 1200comprises an outer ring 1210, an inner ring 1230, and a sheath 1250,which in the illustrated embodiment, comprises a flexible membrane 1252and a plurality of proximally extending bands 1260. A distal end 1264 ofeach band 1260 is secured to the distal ring 1230. A proximal end 1262of each band 1260 extends through an opening 1214 through the outer ring1210. As best seen in the detail view in FIG. 12B, the proximal end 1262of the band 1260 comprises a plurality of transverse grooves 1266 whichdefine a ratcheting surface. The outer ring 1210 comprises a pawl 1212juxtaposed with the opening 1214. The pawl 1212 engages the grooves 1266of the ratcheting surface. The illustrated embodiment of the pawl 1212is also disengageable from the grooves 1266. Embodiments of theratcheting surface and pawl 1212 are similar to corresponding elementsin cable ties and zip ties. The grooves 1266 and pawl 1212 in theengaged position maintain a desired position of the band 1260, andconsequently, the relative positions of the outer ring 1210 and theinner ring 1230. Hence, the mechanism permits a user to adjust andmaintain the relative positions of the outer ring 1210 and the innerring 1230, and consequently, a desired tension in the bands 1260 inretracting tissue.

Those skilled in the art will understand that similar principles areapplicable to similar embodiments, for example, in which the bandscomprise a plurality of enlarged or bead-like portions that engagesuitably dimensioned notches in an outer ring, or in which bands and theouter ring comprise complementary hook-and-loop fasteners. In otherembodiments, the bands are laces that alternately pass through openingsin the outer ring and inner ring and are lockable, for example, by tyingtogether, tying off, clamps, clips, wedges, and the like.

In an embodiment illustrated in a top cross section in FIG. 14, theinner ring 1430 has an adjustable diameter. In the illustratedembodiment, the inner ring 1430 comprises an elongate, tubular body 1432defining a lumen 1434, wherein the body 1432 comprises a first end 1436,a second end 1438, and an opening 1440 into the lumen 1434 at the firstend 1436. An elongate shaft 1442 extends from the second end 1438 of thebody 1432. In the illustrated embodiment, cross sections of the lumen1434 and opening 1440 have the same dimensions. The shaft 1442 isdimensioned to be received through the opening 1440 and into the lumen1434, thereby defining a ring. Telescoping the shaft 1442 in or out ofthe body 1432 adjusts the diameter of the inner ring 1430.

In the embodiment of the inner ring 1530 illustrated in cross section inFIG. 15, the body 1432 is C-shaped, defining a channel 1534 into which asuitably dimensioned shaft 1542 is received.

In some embodiments of the above inner rings, the shaft is selectivelylockable in the body, for example, using a ratchet and pawl, compressingthe opening and/or lumen/channel, threads, locknuts, lock rings,friction, and the like. In the embodiment illustrated in FIG. 14, a topview of the inner ring 1430 is generally circular. In other embodiments,the inner ring has another shape as described above. Other embodimentscomprise a plurality of bodies and shafts. In some embodiments, the bodyis two-ended, that is, each end of the body is dimensioned to receive ashaft telescopically, and the shaft is also two-ended, that is, each endof the shaft is insertable into a body. Some embodiments of the outerring are similarly adjustable.

In an embodiment illustrated in perspective in FIG. 16, the inner anchor1630 comprises a plurality of hooks 1632 disposed around a distal end1654 of the sheath 1650, which when inserted into tissue, anchor thedistal end 1654 of the sheath 1650. In the illustrated embodiment, twohooks 1632 are combined into a single anchoring unit. Other embodimentsuse individual hooks 1632 in each anchoring unit, multiple hooks 1632,or a combination thereof. Embodiments of outer anchors also comprisesimilar hooks.

Some embodiments of the outer anchor comprise an adhesive. In theseembodiments a proximal portion 152 of the sheath 150 (FIG. 1A) is simplyadhered to a patient's skin, for example, using one at least one of apressure sensitive adhesive, a UV curing adhesive, a two-part adhesive,and the like.

FIGS. 17A-17C illustrate embodiments of retractors 1700 similar to theembodiments discussed above, comprising an outer ring 1710, and innerring 1730, and a sheath 1750. In the illustrated embodiments, the sheath750 comprises metal fibers and/or strands, for example, stainless steel,nitinol, titanium, and the like, which are autoclavable. The embodimentof the sheath 1750 illustrated in FIG. 17A comprises a mesh comprisinglinked loops 1752, for example, similar to chain mail. In otherembodiments, the sheath 1750 comprises loops 1752 that are notinterlinked, but are joined, for example, with thread or wire extendingthrough adjacent loops longitudinally, circumferentially, diagonally, ora combination thereof. In the embodiment of the retractor 1700illustrated in FIG. 17B, the sheath 1750 comprises braided wire. In theembodiment of the retractor 1700 illustrated in FIG. 17C, the sheath1750 comprises a plurality of chains 1752, which are an embodiment ofthe bands, strips, and/or sheets discussed above. In the illustratedembodiment, the outer ring 1710 is similar to the embodimentsillustrated in FIGS. 8A, 9A, and 11A. In some embodiments, the sheath1750 further comprises a polymer film is disposed around the metalcomponents in use, thereby protecting the incision or wound, asdiscussed above. In some embodiments of the sheath 1750 or portionthereof illustrated in FIGS. 17A-17C, the metal component issupplemented by or replaced with another material, for example, anengineering plastic, ceramic, a fiber reinforced composite, and thelike.

FIG. 13 is an exploded view of an embodiment of a retractor 1300,similar to the embodiments described above, comprising an outer ring1310, an inner ring 1330, and a tubular sheath 1350, and furthercomprising a shield 1370. The shield 1370 is dimensioned for insertioninto an access channel 1306. The shield comprises a proximal radialflange 1372 and a tubular portion 1380 extending distally from anopening 1374 in the flange 1372. In the illustrated embodiment, thetubular portion 1380 comprises a plurality of elongate fingers 1382,which define narrow gaps 1384 therebetween. In other embodiments, thetubular portion has a different configuration, for example, overlappingfingers, a tube, and the like. In the illustrated embodiment, thefingers 1382 converge. In other embodiments, the fingers do notconverge, for example, are generally parallel, or diverge. In someembodiments, distal ends of the fingers 1382 diverge, thereby defining afunnel that directs instruments on withdrawal.

The flange 1372 is dimensioned to be supported either by the outer ring1302, or in the illustrated embodiment, by tissue (skin) around anincision or opening. The opening 1374 is dimensioned to receive thelargest instrument contemplated in a procedure. The flange 1372 also aportion of the sheath 1350 on which it is disposed and the underlyingtissue. In the illustrated embodiment, the flange 1372 also defines afunnel for instrument insertion into the tubular portion 1380.

The shield 1370 is manufactured as a single assembly or as multiplecomponents that are assembled into the final product. The illustratedembodiment of the shield 1370 comprises flexible or semi-rigid fingers1382. The flange 1372 is rigid, semi-rigid, or flexible. The shield 1370suitably comprises materials similar to those described above assuitable for the sheath. In some embodiments, the shield 1370 comprisesa polymer. In some embodiments, the inner surfaces of the tubularportion 1380 are smooth.

In use, the retractor 1300 is used to retract an incision or opening asdescribed below. The shield 1370 is then inserted into the accesschannel 1306 through the proximal end 1302 of the retractor 1300. Theshield 1370 provides additional protection to the sheath 1350, andconsequently, the retracted tissue. The shield 1370 may be removed whereadditional space is required for a procedure, or where the procedurepresents reduced risk of tissue injury or trauma.

A method for retracting a body wall is described with reference to theembodiment of the retractor 100 illustrated in FIGS. 1A and 1B, althoughthe method is applicable to any of the embodiments described herein.

The inner anchor or inner ring 130 is inserted though an incision,wound, or opening in the body wall. In some embodiments, inserting theinner ring 130 is facilitated by folding or collapsing the inner ring130 prior to insertion. After insertion, the inner ring 130 is thenunfolded, expanded, or deployed in the tissue in interior of the body,as described above. On completing this step, the inner ring 130 isdisposed within the body, the sheath 150 extends out of the incision,and the outer anchor or outer ring 150 is disposed outside the body.

The distal end 152 of the sheath 150 is then pulled towards the user,thereby tensioning the sheath 150. The outer anchor 110 is thendeployed. In the illustrated embodiment, deploying the outer anchorcomprises rotating the outer ring 110 around the annular axis, therebyrolling the sheath 150 therearound, and shortening the length of thesheath 150 between the inner ring 130 and the outer ring 110. Asdiscussed above, the outer ring 110 is rotatable in two directions:rolling-in or inversion, and rolling-out or eversion. Either rotationaldirection effectively rolls the sheath 150 therearound. As discussedabove, in some embodiments, one direction is preferred over the other.On continued rolling, the outer ring 110 contacts the outer surface ofthe body wall, while the inner ring 130 contacts the inner surface ofthe body wall. Continued rolling of the outer ring 110 creates a desiredtension on the sheath 150, thereby retracting the incision. Rolling theouter ring 110 is discontinued at a desired degree of retraction.

Also as discussed above, rotating the outer ring 110 around the annularaxis occurs in discrete steps or increments. In the illustratedembodiment, the outer ring 110 comprises equilibrium or detent positions180° apart. In these equilibrium or detent positions, the outer ring 110resists rotation around the annular axis. Consequently, the outer ring110 resists unrolling under the retracting tension of the sheath 150.

When unretracting or releasing the retractor, the sheath 150 is unrolledfrom the outer ring 110 by reversing the rolling direction of outer ring110, thereby releasing the tension in the sheath 150. The inner ring 130is then removed from the body cavity. As discussed above, in someembodiments, the inner ring 130 is folded or collapsed within the bodycavity, thereby facilitating removal. As discussed above, in someembodiments, removing the inner ring 130 comprises pulling a tethersecured thereto.

While certain embodiments have been particularly shown and describedwith reference to exemplary embodiments thereof, it will be understoodby those of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopethereof as defined by the following claims

1. (canceled)
 2. A tissue retractor comprising: a longitudinal axis defining an instrument access channel extending from a proximal end to a distal end; an outer ring; an inner ring that comprises an elongate tubular body that defines a lumen, wherein a diameter of the inner ring is adjustable, and wherein the elongate tubular body comprises: an opening into the lumen at a first end of the elongate tubular body, and an elongate shaft that extends from a second end of the elongate tubular body, the elongate shaft adapted to be received through the opening at the first end into the lumen thereby defining a ring; and a flexible sheath extending between the outer ring and the inner ring, wherein the instrument access channel extends through the outer ring, the inner ring, and the sheath.
 3. The tissue retractor of claim 2, wherein the inner ring is thinned or flattened at least at an outer circumference of the inner ring.
 4. The tissue retractor of claim 2, wherein the inner ring is radially flat thereby providing the inner ring with a washer-like shape.
 5. The tissue retractor of claim 2, wherein a thickness of a radial cross-section at an inner circumference of the inner ring is greater than a thickness of the radial cross-section at an outer circumference of the inner ring.
 6. The tissue retractor of claim 2, wherein the inner ring comprises a single piece.
 7. The tissue retractor of claim 2, wherein the inner ring comprises a plurality of pieces assembled into the inner ring.
 8. The tissue retractor of claim 2, further comprising a locking means that locks the elongate shaft in the lumen of the elongate tubular body to thereby fix the diameter of the inner ring.
 9. The tissue retractor of claim 2, wherein the elongate tubular body is C-shaped, wherein the C-shaped elongate tubular body defines a channel, and wherein the elongate shaft is adapted to be received into the channel defined by the C-shaped elongate tubular body.
 10. The tissue retractor of claim 9, further comprising a locking means that locks the elongate shaft in the channel of the C-shaped elongate tubular body to thereby fix the diameter of the inner ring.
 11. The tissue retractor of claim 2, wherein dimensions of the lumen and the opening at the first end of the elongate tubular body are the same.
 12. The tissue retractor of claim 2, wherein the adjustments to the diameter of the inner ring are performed by corresponding movements of the elongate shaft in or out of the elongate tubular body.
 13. The tissue retractor of claim 8, wherein the locking means comprises compression of the opening and/or lumen of the elongate tubular body. 